The present invention generally relates to an electrical socket, such as a pin grid array (PGA) socket. More specifically, certain embodiments of the present invention relate to a zero insertion force (ZIF) PGA socket with a spring assisted actuation lever.
Heretofore, ZIF PGA sockets have been proposed that include a base and cover slidably mounted together. The sliding motion between the base and cover is controlled with an actuator through numerous methods in conventional ZIF PGA sockets. For example, U.S. Pat. No. 5,256,080 discloses a bale actuated ZIF socket, while U.S. Pat. No. 4,498,725 discloses a PGA socket having an L-shaped lever that moves the cover. The PGA sockets of the '080 and '725 patents have actuators typically (but not always) that are configured to operate over a 90-degree range of rotation. As the actuator is rotated from one end point to the opposite end of this 90-degree range of rotation, the actuator moves the cover between fully opened and fully closed positions. The foregoing sockets, however, do not meet the space requirements placed on current designs. Consequently, new sockets have been proposed having different actuators that afford a more space efficient overall socket configuration.
For example, recently, a socket has been introduced, in which the cover and base are movable between open and closed positions along a socket longitudinal axis by an actuator that is aligned to rotate about a rotational axis that is parallel to the socket longitudinal axis. The actuator moves the cover and base between open and closed positions or states as the actuator is rotated about the rotational axis. A PGA socket of this type is described in U.S. Pat. No. 6,338,639.
However, certain embodiments of the socket of the '639 patent, while more space efficient, utilize a longer actuator range of motion than previous sockets. For example, the actuator may rotate through a 135-degree range of  rotation to move the cover between fully opened and closed positions. This extended range of motion has caused some confusion for users who normally expect the cover to be fully opened when the actuator is rotated 90 degrees from its closed position as with previous sockets. Consequently, sockets having the longer range of rotation for the actuator are sometimes not fully opened prior to the user attempting to load an electronic package therein. The electronic package may become damaged if loaded when the cover is only partially opened. Such damage may arise if pins on the electronic package are forced into a partially open pin hole array in the cover. The pins on the electronic package may also only sit on top of, without becoming fully seated to, the contacts held in the socket. When the pins on the electronic package and the contacts in the socket are only partially joined, a risk exists for arcing during operation. For the foregoing reasons and others, it is desirable that the user fully open the socket before loading an electronic package.
In an attempt to ensure that the socket is fully opened before loading of an electronic package, at least one socket having a longer actuator range of motion (i.e., greater than 90 degrees) includes a spring coupled to an actuator lever to force the lever to a fully open position and to maintain the socket in the open position. The spring, however, is located externally to the base and the cover on the actuator lever, and the actuator lever must be modified to accommodate the spring. Specifically, the length of the actuator lever must be increased to allow room for the spring. Increasing the lever length is undesirable as it increases the space occupied by the socket in use.